{
  "id": 5484519,
  "title": "Sea stickleback genome reveals repeated chromosomal rearrangements in sticklebacks",
  "url": "https://urgent.news/2026/09/03/sea-stickleback-genome-reveals-repeated-chromosomal-rearrangements-in",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-03T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.08.30.747834v1?rss=1"
  },
  "original_language": "en",
  "account": "A comprehensive analysis of the sea stickleback genome has unveiled repeated chromosomal rearrangements within stickleback species. Sea sticklebacks, also known as fifteen-spined sticklebacks (Spinachia spinachia), possess the smallest chromosome count among sticklebacks, with 2n=40. This research, utilizing PacBio HiFi and Hi-C reads, resulted in a high-quality diploid genome assembly of 407.5 Mb, containing 20 chromosomes and 98.96% complete single-copy BUSCO genes. By comparing five stickleback species and four outgroup genomes, the study established S. spinachia as the sister species to Apeltes quadracus, the four-spined stickleback, rather than a sister group to all sticklebacks. The findings reveal that S. spinachia exhibits one species-specific chromosome fusion and shares two fusions with its close relative, the three-spined stickleback (Gasterosteus aculeatus), which are absent in its sister species. One of these shared fusions, also found in Pungitius, suggests that this fusion is ancestral to the Gasterosteidae family, with a subsequent fission in Apeltes. This implies a lower ancestral chromosome number in Gasterosteidae (2n=44) than previously believed. The convergence of the shared fusion with G. aculeatus highlights an additional case of chromosomal evolution. Overall, the research suggests that karyotype evolution in Gasterosteidae has been influenced by ancestral chromosome fusion, convergent fusion, and secondary fission events.",
  "summary": "Sticklebacks (Gasterosteidae) encompass model organisms which are of particular interest for evolutionary and ecological genomics. Within Gasterosteidae, chromosome number is variable (2n=40-46) and independent fusions of homologous chromosomes have been proposed. The sea stickleback (or fifteen-spined stickleback, Spinachia spinachia ) has the lowest known number of chromosomes (2n=40) and hence…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}